Effects of milrinone versus epinephrine on left ventricular relaxation after cardiopulmonary bypass following myocardial revascularization: assessment by color m-mode and tissue Doppler

Abstract

Objective: The purpose of this study was to evaluate the left ventricular lusitropic effects of epinephrine versus milrinone after cardiopulmonary bypass.

Design: Prospective randomized study.

Setting: Single institution, university teaching hospital.

Participants: Adult patients undergoing coronary artery bypass grafting under cardiopulmonary bypass.

Interventions: After separation from cardiopulmonary bypass, patients were randomized to receive intravenous epinephrine by continuous infusion (0.03 microg/kg/min) or milrinone (50 microg/kg followed by 0.5 microg/kg/min). Transesophageal echocardiographic evaluation of left ventricular diastolic function, with emphasis on relaxation, was performed before and after bypass and after the administration of either epinephrine or milrinone.

Measurements and main results: Measurements included pulse-wave Doppler analysis of mitral inflow and pulmonary vein and left ventricular outflow tract velocities. Left ventricular inflow velocity of propagation measured with color M-mode and tissue Doppler assessment of early mitral annulus velocity were used to evaluate left ventricular relaxation. Values of velocity of propagation and mitral annulus velocity improved significantly after bypass, suggesting improved relaxation. The administration of either epinephrine or milrinone did not result in further improvement in left ventricular relaxation.

Conclusions: After cardiopulmonary bypass, left ventricular relaxation was significantly improved. Neither epinephrine nor milrinone exhibited favorable lusitropic effects after bypass.